Refine
Year of publication
Document Type
- Article (332) (remove)
Has Fulltext
- yes (332)
Is part of the Bibliography
- no (332)
Keywords
- e +-e β Experiments (11)
- BESIII (10)
- Hadron-Hadron Scattering (8)
- Branching fraction (7)
- Heavy Ion Experiments (7)
- Quarkonium (6)
- Particle and Resonance Production (5)
- Collective Flow (4)
- Electroweak interaction (4)
- Exotics (4)
Institute
By analyzing (448.1Β±2.9)Γ106ββπβ‘(3686) events collected with the BESIII detector operating at the BEPCII collider, the decays of ππβ’π½βΞβ’
Β―Ξβ’π (π½=0, 1, and 2) are observed for the first time with statistical significances of 13.9β’π, 6.7β’π, and 8.2β’π, respectively. The product branching fractions of πβ‘(3686)βπΎβ’ππβ’π½ and ππβ’π½βΞβ’Β―Ξβ’π are measured. Dividing by the world averages of the branching fractions of πβ‘(3686)βπΎβ’ππβ’π½, the branching fractions of ππβ’π½βΞβ’Β―Ξβ’π decays are determined to be (2.31Β±0.30Β±0.21)Γ10β4, (5.86Β±1.38Β±0.68)Γ10β5, and (1.05Β±0.21Β±0.15)Γ10β4 for π½=0, 1 and 2, respectively, where the first uncertainties are statistical and the second systematic.
Using a data sample corresponding to an integrated luminosity of 11.3ββfbβ1 collected at center-of-mass energies from 4.23 to 4.70 GeV with the BESIII detector, we measure the product of the π+β’πββπ+β’πββ’π2β‘(3823) cross section and the branching fraction β¬β‘[π2β‘(3823)βπΎβ’ππβ’1]. For the first time, resonance structure is observed in the cross section line shape of π+β’πββπ+β’πββ’π2β‘(3823) with significances exceeding 5β’π. A fit to data with two coherent Breit-Wigner resonances modeling the βπ -dependent cross section yields πβ‘(π
1)=4406.9Β±17.2Β±4.5ββMeV/π2, Ξβ‘(π
1)=128.1Β±37.2Β±2.3ββMeV, and πβ‘(π
2)=4647.9Β±8.6Β±0.8ββMeV/π2, Ξβ‘(π
2)=33.1Β±18.6Β±4.1ββMeV. Though weakly disfavored by the data, a single resonance with πβ‘(π
)=4417.5Β±26.2Β±3.5ββMeV/π2, Ξβ‘(π
)=245Β±48Β±13ββMeV is also possible to interpret data. This observation deepens our understanding of the nature of the vector charmoniumlike states. The mass of the π2β‘(3823) state is measured as (3823.12Β±0.43Β±0.13)ββMeV/π2, which is the most precise measurement to date.
Using about 23ββfβ’bβ1 of data collected with the BESIII detector operating at the BEPCII storage ring, a precise measurement of the π+β’πββπ+β’πββ’π½/π Born cross section is performed at center-of-mass energies from 3.7730 to 4.7008 GeV. Two structures, identified as the πβ‘(4220) and the πβ‘(4320) states, are observed in the energy-dependent cross section with a significance larger than 10β’π. The masses and widths of the two structures are determined to be (π,Ξ)=(4221.4Β±1.5Β±2.0ββMeV/π2,41.8Β±2.9Β±2.7ββMeV) and (π,Ξ)=(4298Β±12Β±26ββMeV/π2,127Β±17Β±10ββMeV), respectively. A small enhancement around 4.5 GeV with a significance about 3β’π, compatible with the πβ‘(4415), might also indicate the presence of an additional resonance in the spectrum. The inclusion of this additional contribution in the fit to the cross section affects the resonance parameters of the πβ‘(4320) state.
Using data samples with an integrated luminosity of 19 fbβ1 at twenty-eight center-of-mass energies from 3.872 GeV to 4.700 GeV collected with the BESIII detector at the BEPCII electron-positron collider, the process e+eβ β Ξ·Ο+Οβ and the intermediate process e+eβ β Ξ·Ο0 are studied for the first time. The Born cross sections are measured. No significant resonance structure is observed in the cross section lineshape.
The singly Cabibbo suppressed decay Ξ+πβπβ’πβ² is measured using 4.5ββfbβ1 of π+β’πβ collision data collected at center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII. Evidence for Ξ+πβπβ’πβ² with a statistical significance of 3.6β’π is reported with a double-tag approach. The Ξ+πβπβ’πβ² absolute branching fraction is determined to be (5.6β’2+2.46β2.04Β±0.26)Γ10β4, where the first and second uncertainties are statistical and systematic, respectively. Our result is consistent with the branching fraction obtained by the Belle collaboration within the uncertainty of 1β’π.
A search for a massless dark photon πΎβ² is conducted using 4.5ββfbβ1 of π+β’πβ collision data collected at center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII. No significant signal is observed, and the upper limit on the branching fraction β¬β‘(Ξ+πβπβ’πΎβ²) is determined to be 8.0Γ10β5 at 90% confidence level.
Using a data sample corresponding to an integrated luminosity of 2.93ββfbβ1 collected at a center-of-mass energy βπ =3.773ββGeV by the BESIII detector, the decay π·0βπβ’π is observed for the first time. The branching fraction is measured to be (6.48Β±0.96Β±0.40)Γ10β4 with a significance of 6.3β’π, where the first and second uncertainties are statistical and systematic, respectively. An angular analysis reveals that the π and π mesons from the π·0βπβ’π decay are transversely polarized. The 95% confidence level upper limit on longitudinal polarization fraction is set to be less than 0.24, which is inconsistent with current theoretical expectations and challenges our understanding of the underlying dynamics in charm meson decays.
From December 2019 to June 2021, the BESIII experiment collected about 5.85 fbβ1 of data at center-of-mass energies between 4.61 GeV and 4.95 GeV. This is the highest collision energy BEPCII has reached so far. The accumulated e+eβ annihilation data samples are useful for studying charmonium(-like) states and charmed-hadron decays. By adopting a novel method of analyzing the production of Ξ+cΞΒ―βc pairs in e+eβ annihilation, the center-of-mass energies are measured with a precision of βΌ0.6 MeV. Integrated luminosities are measured with a precision of better than 1\% by analyzing the events of large-angle Bhabha scattering. These measurements provide important inputs to the analyses based on these data samples.
The integrated luminosities of data samples collected in the BESIII experiment in 2016β2017 at center-of-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events. The integrated luminosities of old datasets collected in 2010β2014 are updated by considering corrections related to detector performance, offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter, which can haphazardly occur.
The hadronic decay ππβ‘(2β’π)β3β’(π+β’πβ) is observed with a statistical significance of 9.3 standard deviations using (448.1Β±2.9)Γ106ββπβ‘(3686) events collected by the BESIII detector at the BEPCII collider. The measured mass and width of ππβ‘(2β’π) are (3643.4Β±2.3β(stat)Β±4.4β(syst))ββMeV/π2 and (19.8Β±3.9β(stat)Β±3.1β(syst))ββMeV, respectively, which are consistent with the world average values within two standard deviations. The product branching fraction β¬β‘[πβ‘(3686)βπΎβ’ππβ‘(2β’π)]Γβ¬β‘[ππβ‘(2β’π)β3β’(π+β’πβ)] is measured to be (9.2Β±1.0β(stat)Β±1.2β(syst))Γ10β6. Using β¬β‘[πβ‘(3686)βπΎβ’ππβ‘(2β’π)]=(7.β’0+3.4β2.5)Γ10β4, we obtain β¬β‘[ππβ‘(2β’π)β3β’(π+β’πβ)]=(1.31Β±0.15β(stat)Β±0.17β(syst) (+0.64β0.47)β(extr))Γ10β2, where the third uncertainty is from β¬β‘[πβ‘(3686)βπΎβ’ππβ‘(2β’π)]. We also measure the ππβ’π½β3β’(π+β’πβ) (π½=0, 1, 2) decays via πβ²βπΎβ’ππβ’π½ transitions. The branching fractions are β¬β‘[ππβ’0β3β’(π+β’πβ)]=(2.080Β±0.006β(stat)Β±0.068β(syst))Γ10β2, β¬β‘[ππβ’1β3β’(π+β’πβ)]=(1.092Β±0.004β(stat)Β±0.035β(syst))Γ10β2, and β¬β‘[ππβ’2β3β’(π+β’πβ)]=(1.565Β±0.005β(stat)Β±0.048β(syst))Γ10β2.